Technical Field
The technique of the present disclosure relates to a signal processing device, a magnetic information playback device, and a signal processing method.
Related Art
U.S. Pat. No. 7,602,863 B2 discloses a technique whereby the phase of a signal that is input at the input stage of a phase adjustment circuit is adjusted by feeding back the output of a decoder to the input stage of the phase adjustment circuit. Further, in the technique described in U.S. Pat. No. 7,602,863 B2, optimal feedback corresponding to a decoded pattern is enabled by installing an independent phase adjustment circuit for each possible decoding pattern.
In J. Xie and B. V. K. V. Kumar, “Timing Recovery Loop Delay Compensation by Optimal Loop Gains”, in Proc. ICC, 2006, pp. 3229-3234 (referred to below as “the non-patent document”), a technique is described in which, even in a system in which delays exist in feedback to the input stage of a phase adjustment circuit, feedback delays can be suppressed to a minimum by optimizing the gain parameters of the phase adjustment circuit.
U.S. Pat. No. 7,885,030 B2 discloses a method that, because plural channels in a tape system are simultaneously influenced by speed fluctuations, improves resistance to jitter by using information on speed fluctuations obtained from the playback signals of other channels rather than only from the signal from a single channel.
However, in the technique described in U.S. Pat. No. 7,602,863 B2, since the final output of the decoder is fed back, it is difficult to immediately adjust the phase of a signal that is input at the input stage of the phase adjustment circuit. While it is possible to suppress reductions in immediacy by installing plural phase adjustment circuits and plural buffer memories, the scale of the circuit becomes enormous.
Further, in the technique described in the non-patent document, since the reliability of the signal that is fed back to the input stage of the phase adjustment circuit is low, the phase adjustment circuit becomes unable to function properly.